package panda.lang.escape;

/**
 * Translates codepoints to their Unicode escaped value suitable for Java source.
 * 
 */
public class JavaUnicodeEscaper extends UnicodeEscaper {

	/**
	 * <p>
	 * Constructs a <code>JavaUnicodeEscaper</code> above the specified value (exclusive).
	 * </p>
	 * 
	 * @param codepoint above which to escape
	 * @return the newly created {@code UnicodeEscaper} instance
	 */
	public static JavaUnicodeEscaper above(final int codepoint) {
		return outsideOf(0, codepoint);
	}

	/**
	 * <p>
	 * Constructs a <code>JavaUnicodeEscaper</code> below the specified value (exclusive).
	 * </p>
	 * 
	 * @param codepoint below which to escape
	 * @return the newly created {@code UnicodeEscaper} instance
	 */
	public static JavaUnicodeEscaper below(final int codepoint) {
		return outsideOf(codepoint, Integer.MAX_VALUE);
	}

	/**
	 * <p>
	 * Constructs a <code>JavaUnicodeEscaper</code> between the specified values (inclusive).
	 * </p>
	 * 
	 * @param codepointLow above which to escape
	 * @param codepointHigh below which to escape
	 * @return the newly created {@code UnicodeEscaper} instance
	 */
	public static JavaUnicodeEscaper between(final int codepointLow, final int codepointHigh) {
		return new JavaUnicodeEscaper(codepointLow, codepointHigh, true);
	}

	/**
	 * <p>
	 * Constructs a <code>JavaUnicodeEscaper</code> outside of the specified values (exclusive).
	 * </p>
	 * 
	 * @param codepointLow below which to escape
	 * @param codepointHigh above which to escape
	 * @return the newly created {@code UnicodeEscaper} instance
	 */
	public static JavaUnicodeEscaper outsideOf(final int codepointLow, final int codepointHigh) {
		return new JavaUnicodeEscaper(codepointLow, codepointHigh, false);
	}

	/**
	 * <p>
	 * Constructs a <code>JavaUnicodeEscaper</code> for the specified range. This is the underlying
	 * method for the other constructors/builders. The <code>below</code> and <code>above</code>
	 * boundaries are inclusive when <code>between</code> is <code>true</code> and exclusive when it
	 * is <code>false</code>.
	 * </p>
	 * 
	 * @param below int value representing the lowest codepoint boundary
	 * @param above int value representing the highest codepoint boundary
	 * @param between whether to escape between the boundaries or outside them
	 */
	public JavaUnicodeEscaper(final int below, final int above, final boolean between) {
		super(below, above, between);
	}

	/**
	 * Converts the given codepoint to a hex string of the form {@code "\\uXXXX\\uXXXX"}
	 * 
	 * @param codepoint a Unicode code point
	 * @return the hex string for the given codepoint
	 */
	@Override
	protected String toUtf16Escape(final int codepoint) {
		final char[] surrogatePair = Character.toChars(codepoint);
		return "\\u" + hex(surrogatePair[0]) + "\\u" + hex(surrogatePair[1]);
	}

}
